Process for the exploitation of bitumens containing strata by underground preparation and gasification



United States Patent PROCESS FOR THE EXPLOITATION 0F BITUMENS-CONTAINING STRATA BY UNDERGROUND PREPARATION AND GASIFICATION HansLange, Wietze Kreis Celle, Germany, and Gunther Schlicht, deceased, lateof Hamburg, Germany, by Erika Marie Elisabeth Schlicht, legalrepresentative, Hamburg-Othmarschen, Germany, assignors to DeutscheErdol-Aktiengesellschaft, Hamburg, Germany No Drawing.Continuation-in-part of application Ser. No. 242,868, Dec. 3, 1962. Thisapplication Oct. 23, 1965, Ser. No. 505,141

7 Claims. (Cl. 166-36) This application is a continuation-in-part ofapplication Ser. No. 242,868, filed Dec. 3, 1962, now U.S. Patent No.3,279,540, and applicants rely upon the disclosure, rights andpriorities contained therein.

This invention relates to an improved method for conditioningunderground coal deposits and extracting bitumens from the ground.

It is known to create an underground generator in a bitumens-containingstrata where the generator is bounded by so-called cleavage lineboreholes and treatment boreholes for division of the generator intotreatment sections to simultaneously or successively treat the strata.It is also known to introduce a heat-transfer medium into a treatmentborehole under pressure along with heating of the medium 'by circulationthrough a nuclear reactor or other heat source. By this method bitumensin an underground strata are dislodged and heated so as to form energyrich masses which can produce or be converted into gases. The treatmentsections may be worked simultaneously or successively because the heatintroduced through the treatment boreholes must follow predeterminedpaths in its passage through the strata. In this manner, it has beenpossible for the heat which has spread out laterally from the treatmentborings to be brought as initial heat to the strata to be gasified andafter gasification of one such section of the underground generator tomake use of the stored heat in the upper strata for preheating thegasification air that is on its way to the other sections of theunderground generator.

The burning and gasification zone of the underground generator thusreceives at every time and in every subsection, additional heat, wherebyit is kept at a high temperature and provides a well preheated roofstructure so that the advancing burning and gasification zone can alwaysbe kept at an advantageously high temperature.

This reaction heat in the underground generator, which has beenintensified by circulating the heat transfer medium in heat exchangewith a nuclear reactor, and which has a high energy value, can bereferred to as double thermal impact.

If this uncontrolled nuclear fission in the reactor cannot or must notoccur, then the coal will not be subjected either to the powerfulmechanical shock or to the increased heat.

When the double thermal impact stops, the ensuing gasification processwill go on more slowly and at a lower temperature, so that in thetemperature region of 340- 425 C., the coal will be softened over awider region. As a result, the fissure or pore formation which has beenstarted, is diminished or reversed and inadequate yield or poor qualityof the gas resents a problem.

It is an object of this invention to use various measures and steps tocorrect the unfavorable effects on the gasification process which resultfrom an inadequate disruption of the coal after cessation of the doublethermal impact.

It is a particular object of the present invention to prepare a depositof coal for extraction when the temperature of the coal deposit is inthe plastic temperature range.

3,395,756 Patented Aug. 6, 1968 Upon further study of the specificationand appended claims, other objects and advantages of this invention willbecome apparent.

To attain these objects, there is provided the following modifiedprocedure. It is defined as follows:

(1) Selecting a heat transfer medium comprising a mixture ofnon-condensible gases and a mixture of condensible hydrocarbons havingdifferent boiling points between 250 and 300 C. and heating the heattransfer medium;

(2) Introducing the heated heat transfer medium through treatmentboreholes into a coal deposit at a pressure above the fracturingpressure of the coal, creating fissures and shear surfaces in the coalstratum and heating the fissures and shear surfaces to just below thesoftening point of coal which is 340 to 425 C.;

(3) Cooling the treatment borings by the circulation of unheated liquidlight hydrocarbons;

(4) Introducing a mixture of oxygen carriers or dissolved explosives inlow boiling hydrocarbons having a vaporization temperature below thesoftening temperature of the coal and vaporizing all solvents bysubsequent injection of hot heat transfer medium to precipitate theexplosives or oxygen carriers in highly active form;

(5) Introducing air and hydrocarbon vapors into the treatment borings atpressures greater than the breaking pressure of the coal, igniting andburning the mixtures in the previously formed fissures and shearsurfaces whereby the applied pressure keeps the fissures open during theplastic state of the coal until the upper temperature limit of 425 C. isexceeded and continuation of the process until flow resistance issubstantially diminished and products of combustion are collected fromrecovery boreholes; and

(6) Introduction of oxidizing agents and commencement of the regularcombustion of the coke resulting from the previous steps.

(The materials are introduced into the strata through boreholes whichare generally vertical. If the work is being done from shafts orexcavations, then the boreholes are generally horizontal.)

With respect to the details of steps 1 and 2, condensible hydrocarbonsare used as the heat transfer media, and are passed through a heatexchanger for receiving heat (about 350 C.) from a heat source such asan atomic reactor, and under pressure sufficient to break theunderground deposits (about 20-35 atm. per 100 m. depth), so that theheat can advance into the strata. Preferably, the hydrocarbon shouldhave a normal boiling point of about not less than 50 C. Specificexamples of such hydrocarbons are benzene or a mixture of 10% pentane,25% hexane and 65% heptane, or a mixture of 15% pentane and heptane.

In addition, it is necessary to employ incondensable gases such as inertgases, light hydrocarbons such as methane, and gaseous oxygen or air inthe heat transfer medium in predetermined amounts. These added materialswill increase the volume of the heat transfer vapors and will thereforeincrease the depth of penetration thereof into the fissures and cracksof the strata beyond where pure gases would penetrate, and uponcondensation will cause the deposition of large numbers of tiny globuleswhich will furnish many points of support for the adjacent surfaces. Itis thus apparent that the incondensable gases must remain gaseous under200 atm. (absolute) pressure and temperature as low as 150 C. The ratioof condensibles to incondensibles, on a weight basis, is about partscondensibles to about 30 parts, preferably 20 parts incondensibles.

After the strata have been loosened by means of pressure and thermalliquids and gases in the region of the underground generator, smallerexplosions may be set off in the boreholes. The strata are then exposedto pressure waves from the cleavage line borings and also to the weightof the fromations above, which Will cause the entrapped gaseous globulesto become compressed and thus serve to store up energy. After passage ofthe pressure waves, these entrapped globules expand so as to restore theporosity and open up the crevices which existed previously.

After the preliminary treatment steps 1 and 2, steps 3, 4 and 5 areperformed wherein oxygen carriers such as potassium nitrate or dissolvedexplosives are introduced with the heat transfer medium into the strataand distributed over a wide region. Suitable heat transfer materials arehydrocarbon fractions with different boiling points and eventually alsowith separated boiling points so that separate condensations will occur.As a principal heat transfer medium there is preferably used ahydrocarbon fraction which under 1 atm. has a boiling point of 250300 C.Since the heat transfer medium of this invention is always under acertain positive pressure in the strata, it will remain liquid in theheat exchanger of the reactor and will therefore not form incrustationswhich would lower the quantity of heat transferred. In order that theoxygen carriers and the explosives may come into action at certaindistances from the boreholes, low boiling point liquids (B.P. less thanabout 100 C.) are used as their solvents. Such solvents will bevaporized by the previously warmed regions of the strata so as to setfree the dissolved materials which can then become active. At desiredplaces, localized combustion can thus be brought about, which can bepropagated in the presence of combustible gases. Explosive blastingmaterials will also cause gas formation with a breaking up of thestrati. The explosive charges in the cleavage guiding holes arepreferably set off simultaneously. As preferred oxygen carriers orexplosives there can be mentioned TNT, black powder or a mixture of 1 kbenzene and 1.1 kg. oxygen 95%.

As modification of this process, a small preliminary explosion may beset off in the boreholes that have not yet been lined with tubes whichwill initiate the formation of fissures in the immediate surroundings.After the boreholes are redrilled, the fissures and boreholes are againfilled with dissolved explosives so that the principal explosion thusproduced will exert a strongly propagated disrupting action in thestrata.

As solvents for the oxygen producing substances or explosives, certaincomponents of the heat transfer medium that is sent to the treatment orcleavage guiding medium may be used. By gradual or sudden changes in thecornpositions of its components, the heat transfer agent can also bemade to serve as a solvent. Low boiling hydrocarbons are primarlysuitable for this purpose, depending on the desired kind of action.Examples of preferred solvents are benzene, xylene and toluene.

The transport of the oxygen carrier or the explosive and its fixation isaccomplished as follows: A heat transfer medium, after passage throughthe heat exchanger of a reactor, is introduced into the strata which arepartly opened up by fissure formation, warming and partial degassing. Ifthe reactor is only to give off heat, and the uncontrolled nucleardisintegration, as above mentioned, cannot or must not be brought about,then the reactor can obviously be substituted by some other source ofheat, as for example an electrically energized immersion heater or by aheat exchanger supplied by heat from another source.

After the required operation has commenced, a low boiling solvent isintroduced cold into the strata after having by-passed the heatexchanger as in (3) above. After the strata have been locally cooled inthat manner, a solution of an oxygen liberating substance or anexplosive in a volatile solvent is introduced as in step (4) until ithas reached the required distance from the borehole, the distance havingbeen calculated with due consideration to the subsequent introduction ofthe heat carrying medium. The heat transfer medium is then introduced,which after a certain time, will vaporize the solvent that was used forintroducing the oxygen liberating substance or the explosive, so thatthese materials will now be present in highly effective form. Thedissolved explosive is relatively safe to handle. If the separation ofthe explosive by vaporization is impossible or impractical, then use ismade of a solvent which upon mixture with another subsequentlyintroduced solvent will cause precipitation of the explosive or theoxygen carrier.

If a formation that has been thus treated with heat and explosivesbecomes plastic and difiicultly permeable in places, the entrapped gasbubbles or the products of combustion of the introduced hydrocarbons, orof those from the formation, or the gases from the detonated explosives,will cause the strata to again become partly porous after the pressurehas been removed.

In some formations with solid bitumens, it may not be possible toproduce adequate fissures by means of small explosives and pressurewaves. The widely varied structure of coal, the varying depths of coaldeposits, and the different thicknesses of its beds, lead to a widevariety of conditions, and it is therefore necessary to increase thefissure formation which has been initiated by the use of vapors.

This can be accomplished by thermal stresses in the formation, whichwill cause the formation of fissures and will enlarge or supplement thefissures which have been produced by pressure and explosions. Thermalstresses occur when heat is delivered quickly into a restricted portionof the formation, which will produce large temperature differences inclosely adjacent portions of the bitumen or coal. There will then be hotregions in the fissures in immediate proximity to cold regions. Theresulting thermal stresses will produce more fissures, as can beobserved during the heating of coal in retorts or coke ovens.

For this purpose it is necessary that a large quantity of heat beintroduced quickly into the formation and across long and numerouspaths. This is accomplished by a pneumatically accumulated thermal shockdelivering a large amount of heat by means of vapors and gases.

The amount of energy that is introduced by a heated liquid isconsiderable. Injection of m. of a pure liquid under 320 atm. pressurecauses fissure formation over a circumference of m. around the treatmentborehole. If, however, vapors or gases are used instead of the liquid,and are introduced under the same pressure, there will be stored in theformation about 75 m. 320 atm.=24,000 m. of gases and vapors underpressure.

If the energy of the source of heat is not equal to the energy desiredto be stored, then additional heat can be produced by igniting andburning the hydrocarbon and air mixture which passes from the treatmentborehole into the formation. This additional burning is continued untilthe frictional resistance of the opened fissures has become so smallthat the gasification and vaporization can itself be omitted, with theinjection of air alone into the formation.

If the formation is to be rendered porous by fissure and pore formationbetween the treatment borehole and the cleavage directing boreholes byheat and pressure alone and without additional nuclear explosions, theninert gases or air must be added to the medium which delivers heat tothe introduced hydrocarbons, and in amounts sufficient to producestrata-supporting bubbles. In order to introduce the large quantities ofthis gas-air mixture into the treatment boreholes in the most efiicientmanner, and to have convenient control over it both at the inlet and atthe outlet end of the treament borehole, it may be advantageous toperform some preparatory operations in both the treatment and thecleavage guiding boreholes.

For this purpose a small explosion is set off in each borehole toproduce fissures in the immediate neighborhood of the borehole forincreasing the free surface in that region.

After these explosions, the holes are redrilled and lined with casings.In every treatment borehole certain masses of liquid hydrocarbons loadedwith gases for producing strata producing bubbles are injected underpressure greater than the disruption pressure of the formation, wherebyfissure formation will be increased and extended while the gaseousbubbles will keep the fissures open.

It is not considered practical to carry out such treatments with largermasses of liquids (about 0.25 liter per cm. carbon) becauseincompressible liquids will quickly break through any boundary. Thepressure action will then be of only short duration and willspontaneously drop off as soon as a fissure extends all the way over toa cleavage directing borehole so that additional fissures will not beformed, at least not at any great distance from the treatment borehole.Only one such fissure will prevent such an underground generator frombeing operated successfully because it will then be impossible tocontrol the movement of gases and vapors.

If now instead of a liquid, a gas is injected into the coal stratum, itwill, because of its much lower viscosity, penetrate into tiny capillaryfissures and microscopic pores. Since it is compressible, it will storeup a substantial amount of pressure-energy, even though the pressure mayincrease only slowly. If the breaking strength of the formation isexceeded, then fissure formation will result. The pressure, however,drops only slightly, and will be brought up again until the initiallyproduced fissure reaches a cleavage directing borehole. The large amountof stored up gas still contains much pressureenergy, which continues toact on all sides and will produce fissures which will lead to the othercleavage directing boreholes. The accumulation of vapors and gases willthus cause the disruption process to continue for a long time. If thecompressed fluids have much heat stored up in them, then they will passmore quickly through the larger fissures and thus produce strong localheating, which will result in thermal stresses between these hot regionsand adjacent cooler regions, and that will in turn lead to the formationof more fissures.

In recapitulation, it may be stated that the last-described process,which does not involve the setting off of any powerful blasts, iscarried out by first pretreating the boreholes to disrupt the formationin their immediate neighborhoods, and then passing vaporized or liquidhydrocarbons, steam and gases such as air over a heat-exchanger and theninto a treatment borehole under a pressure greater than the fracturingpressure of the formation, until a fissure has broken through under highpressure to a cleavage directing borehole.

In the ensuing second phase, which is characterized by high heatproduction, the mixture of hydrocarbon vapors and air that leaves thetreatment borehole is ignited and generates a substantial amount of heatduring the time that it burns. The thermal strains produced in thismanner cause a widening of the fissures and increased porosity of thecoal.

The ignition of the mixture can be etfected either by means of anelectrically operated igniter, or by a short time admixture of vaporswith an ignition point below the surface temperature of the heatexchanger. Combustion can also be initiated by the use of platinumblack.

In this second phase, the expansion of the forced-in air which hasresulted from the generation of heat has reduced the quantity ofhydrocarbons to such an extent that there will be present an excess ofoxygen which will prevent any occurrence of carbon black which couldcause clogging of the fissures. To compensate for the diminishing supplyof steam at the source of heat, additional water is added for conversioninto steam. In porous formations the steam or the water, possibly mixedwith hydrocarbons which could be very viscous, may conveniently beintroduced through a separate pipe into the formations in which the pipepasses through a packer which separates the upper space where air oroxygenenriched air is used for burning the light hydrocarbons, from thelower space where the second phase is carried out. The movement of thelighter materials in the upper space assists in the movement of thematerials in the lower space in the region of the treatment borehole, asin a direction toward 'a cleavage guiding hole. During the early part ofthe steaming process, a water gas reaction may occur.

Steps 3, 4 and 5 end when the the section that is being treated withpressure and heat has acquired the necessary porosity. In order to avoida deterioration of the heating value of the vaporization gas byadmixture with the products of combustion from the second phase, itshould be terminated as quickly as possible. A time period of about 4days should be sufficient.

Still another modification includes circulating the heat transfer fluidbetween the borings leading to the upper strata of the formation. Theheat transfer medium which has broken through to the cleavage directingborings is brought above ground to be reheated, and is then returned tothe treatment borehole for another passage from the treatment to thecleavage directing borehole. This medium, which is now enriched withhydrocarbons, and from which no products have been separated, iscontinued in circulation until the desired effect is produced. Such aneifect consists of a heating up of the formation together with increasedpermeability and/or porosity. As heat carriers, gaseous hydrocarbonsmixed with liquid hydrocarbons of widely different boiling points may beused.

In step 6 which has now commenced, air alone which has been preheated atthe combustion front of step 5 is introduced for vaporizing anddegassing the bituminous formations. From this point on, the processcontinues as described in our copending patent application Ser. No.216,271, filed Aug. 7, 1962, and now US. Patent No. 3,283,814.

Without further elaboration, it is believed that one skilled in the artcan employ this invention to full advantage. Consequently, the followingpreferred specific embodiments are to be considered exemplary and not inany way limitative of the remainder of the specification and appendedclaims.

EXAMPLE 1 A coal stratum of brittle mineral coal having a thickness of1.50 m. is deposited in a depth of 320 m. A heat source, for instance apower reactor, evaporates in the pressure bore under simultaneousemission of radiation energy, e.g., of 90% of heat energy and 10% ofradiation energy with 500,000 kcaL/h. for preheating for 2-5 days, 500kg. of liquid hydrocarbons having a large boiling range, for instance10% pentane, 25% hexane, 65% heptane and 3,000 Nm. /h. of compressedair, to 320 C. at a pressure of 90 atmospheres absolute. At thispressure the coal cracks and therefore, if said pressure is maintained,the hydrocarbon flows through the coal str-atum. The vaporoushydrocarbons are condensed at the newly formed surfaces of the crevicesin the direction of the depth of the layer according to the boilingpoint of the individual hydrocarbons and retain the compressed air ofthe mixture in a large number of bubbles as supports within thecrevices. When an ignition is caused in the pressure bore after 2-5days, the oxygen of the compressed air burns as much coal in the tracksthat the temperature in said crevices rises to more than 450 0., wherebythe coal is degasified in said cracks and causes the production ofstationary permeable coke. Thereafter, a further progressingdegasification and gasification is possible, for instance, with 12,000Nm. /h. to obtain heated air enriched with of oxygen at a pressure of 15atmospheres absolute at 300 C. until the coal is completely gasified inthe underground generator. The gen- 7 erator gas has a pressure of 12atmospheres absolute, and per 1 kg. of coal there are produced 2.05 Nm.of generator :gas having a heating value of 2,800 kcal./m.

EXAMPLE 2 A coal deposit consisting of a tough elastic mineral coal andhaving a thickness of 2.20 m. is deposited at a depth of 750 m. A heatsource evaporates in the pressure bore at a ratio of 500,000 kcal./h.for preheating for 2-5 days 500 kg./h. of liquid hydrocarbons having alarge 1 boiling range according to Example 1, and 3,000 Nm h. ofcompressed air to 300 C. at a pressure of 240 atmospheres absolute. Atsaid pressure the coal becomes cracky, but the cracks close immediatelyafter the pressure falls below the cracking pressure. In this case thesupporting bubbles alone are not able to keep the cracks open. In orderto obtain a depth effect, the surroundings of the pressure bore arecooled down to a temperature less than 120 C. after the preheating bymeans of cold hydrocarbons, so that a solution of 200 kg. of explosiveTNT containing the threefold quantity of toluene and the twelvefoldquantity of benzene can be distributed in the cracks formed within thepressure bore. After these explosives are distributed, compressed air ina quantity of 3,000 Nm. h. at 240 atmospheres absolute and evaporatedliquid hydrocarbons of a large boiling range in a quantity of S kg./h.,for instance, by weight of pentane and 85% by weight of heptane, arepreheated again in a temperature up to 300 0, whereby the solvents ofthe explosive are evaporated to such an extent that from the preheatingtemperature an auto-ignition of the explosives distributed in the coaloccurs, whereby the temperature in the cracks increases to such anextent, that a degasification occurs and the fusing temperature isexceeded. A heavy, pervious coke is obtained thereby, which makes itpossible to initiate the degasification by means of air enriched withoxygen at a pressure of 15 atmospheres absolute.

EXAMPLE 3 The three uppermost meters of a mineral deposit having athickness of 5 m. and being positioned at a depth of 1200 m. have apermeable structure, whereas the structure of the 2 lowermost meters iscoalesced or scarcely permeable. One operates in the upper portion ofthe pressure bore with a disruption pressure of 360 atmospheresabsolute, and for the rest as described in Example 1. Cold mixturesconsisting of 1.57 kg. of 0 per 1 kg. of hydrocarbons, as for instancebenzene, are introduced at a quantity of 500 kg./h. per 1 kg. ofthickness of the scarcely permeable deposit into the lower portion ofthe deposit at the disruption pressure through a separate conduit andthrough a bore arranged in the lower portion of the packer, for 5-6days. However, it is also possible to use the same quantities of amixture consisting of 3 parts of water and 7 parts of lighterhydrocarbons, as for instance, heptane. Through the progressinggasification in the upper portion of the deposit the occluded liquidsare heated and caused to ignite or evaporate, whereby the lower portionof the deposit is developed for removal of the minerals.

From the foregoing description, one skilled in the art can easilyascertain the essential characteristics of this invention, and withoutdeparting from the spirit and scope thereof, can make various changesand modifications of the invention to adapt it to various usages andconditions. Consequently, such changes and modifications are properly,equitably, and intended to be, within the full range of equivalence ofthe following claims.

We claim:

1. A process for preparing for extraction underground solid bituminousdeposits in the plastic temperature range of the solid bitumenscomprising:

(a) heating above ground a heat transfer medium comprising a mixture ofnon-condensible gases and condensible hydrocarbons;

(b) introducing through treatment boreholes said heat transfer mediuminto said bituminous deposits at a pressure above the breaking pressureof said solid bitumens and at a temperature below the softeningtemperature of said solid bitumens;

(c) introducing cool liquid light hydrocarbons into said treatmentboreholes whereby the area around said boreholes is cooled;

(d) introducing into said bituminous deposits a member selected from thegroup consisting of oxygen-releasing compositions and explosives, saidmember dissolved in volatile solvents and evaporating said solvents bysubsequently introducing a hot fluid medium whereby said member isprecipitated in a solid activated form; and

(e) introducing a mixture of air and hydrocarbon vapors into saidtreatment boreholes at a pressure above the breaking pressure of saidsolid bitumens and igniting said mixture and said precipitated solidactivated form whereby the porosity of said bituminous deposits ismaintained through said plastic temperature range.

2. The process of claim 1 wherein said solid bitumens are coal.

3. The process of claim 1, wherein said condensible hydrocarbons of (a)have boiling points between 250 and 300 C.

4. The process of claim 3, wherein said condensible hydrocarbons are amixture of hydrocarbons having different boiling points in the range 250to 300 C.

5. The process of claim 1, wherein said softening temperature of (b) is340 to 425 C.

6. The process of claim 1, wherein the pressure of (e) is maintainedthrough the 425 C. upper limit of said plastic temperature range.

7. The process of claim 1, further comprising the step of introducingoxidizing agents and extracting said bituminous deposit by vaporizationand gasification.

References Cited UNITED STATES PATENTS 3,004,595 10/1961 Crawford et al.16611 3,034,579 5/1962 Parker 16636 X 3,066,733 12/ 1962 Brandon 166363,075,463 1/1963 Eilers et al. 166- 36 3,266,572 8/1966 Woodward 166383,270,815 9/1966 Osborn et a]. 16636 3,279,540 10/ 1966 Lange et al16636 3,283,814 11/1966 Schlicht et al.

STEPHEN J. NOVOSAD, Primary Examiner.

1. A PROCESS FOR PREPARING FOR EXTRACTION UNDERGROUN SOLID BITUMINOUSDEPOSITS IN THE PLASTIC TEMPERATURE RANGE OF THE SOLID BITUMENSCOMPRISING: (A) HEATING ABOVE GROUND A HEAT TRANSFER MEDIUM COMPRISING AMIXTURE OF NON-CONDENSIBLE GASES AND CONDENSIBLE HYDROCARBONS. (B)INTRODUCING THROUGH TREATMENT BOREHOLES SAID HEAT TRANSFER MEDIUM INOTSAID BITUMINOUS DEPOSITS AT A PRESSURE ABOVE THE BREAKING PRESSURE OFSAID SOLID BITUMENS AND AT A TEMPERATURE BELOW THE SOFTENINGTEMPERATURES OF SAID SOLID BITUMENS; (C) INTRODUCING COOL LIQUID LIGHTHYDROCARBONS INTO SAID TREATMENT BOREHOLES WHEREBY THE AREA AROUND SAIDBOREHOLES IS COOLED; (D) INTRODUCING INTO SAID BITUMINOUS DEPOSTIS AMEMBER SELECTED FROM THE GROUP CONSISTING OG OXYGEN-RELEASINGCOMPOSITIONS AND EXPLOSIVES, SAID MEMBER DISSOLVED IN VOLATILE SOLVENTSAND EVAPORATING SAID SOLVENTS BY SUBSEQUENTLY INTODUCING A HOT FLUIDMEDIUM WHEREBY SAID MEMBER IS PRECIPITATED IN A SOLID ACTIVATED FORM;AND (E) INTRODUCING A MIXTURE OF AIR AND HYDROCARBON VAPORS INTO SAIDTREATMENT BOREHOLES AT A PRESSURE ABOVE THE BREAKING PRESSURE OF SAIDSOLID BITUMENS AND IGNITING SAID MIXTURE AND SAID PRECIPITATED SOLIDACTIVATED FORM WHEREBY THE POROSITY OF SAID BITUMINOUS DEPOSITS ISMAINTAINED THROUGH SAID PLASTIC TEMPERATURE RANGE.